CN110720978A

CN110720978A - Flexible circuit with position and force sensor coils

Info

Publication number: CN110720978A
Application number: CN201910641404.1A
Authority: CN
Inventors: C.T.比克勒; J.T.凯斯; K.J.赫雷拉
Original assignee: Biosense Webster Israel Ltd
Current assignee: Biosense Webster Israel Ltd
Priority date: 2018-07-16
Filing date: 2019-07-16
Publication date: 2020-01-24
Also published as: IL267698B1; US11672461B2; KR20200008956A; US20230293080A1; IL267698A; IL267698B2; JP2020073865A; EP3611486C0; EP4324422A3; EP3611486A1; RU2019121562A; EP4324422A2; US20200015693A1; BR102019014440A2; AU2019204515A1; EP3611486B1; CA3049587A1

Abstract

The invention provides a flexible circuit with position and force sensor coils. The present invention provides a flexible circuit that is substantially planar, which can be assembled into an electrophysiology catheter. The flexible circuit may include various position sensing portions and force sensing portions. The flexible circuit may be deformed in a manner that improves the functionality of the catheter with respect to force feedback and position feedback, and then also deformed to be assembled into a small volume catheter.

Description

Flexible circuit with position and force sensor coils

Cross reference to co-pending patent application

This patent application relates to prior us patent application 15/452,843 filed on 8/3/2017, which is incorporated by reference in its entirety.

Copyright notice

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the patent and trademark office patent file or records, but otherwise reserves all copyright rights whatsoever.

Technical Field

The subject matter disclosed herein relates to instruments for diagnostic and surgical purposes that use catheters to measure force, pressure, or mechanical tension or compression for diagnostic and surgical procedures in the heart.

Background

When a region of cardiac tissue abnormally conducts electrical signals to adjacent tissue, an arrhythmia, such as atrial fibrillation, occurs, disrupting the normal cardiac cycle and causing an arrhythmia.

Protocols for treating cardiac arrhythmias include surgically disrupting the source of the signal causing the arrhythmia, as well as disrupting the conduction pathway for such signals. By applying energy through a catheter to selectively ablate cardiac tissue, it is sometimes possible to block or alter the propagation of unwanted electrical signals from one part of the heart to another. The ablation method breaks the unwanted electrical path by forming a non-conductive ablation lesion.

Disclosure of Invention

Improvements in patient outcome are sought for treatment methods involving ablation of tissue, particularly cardiac tissue. The subject matter disclosed herein relates to structures within an electrophysiology catheter that can be used to provide feedback to a user of the catheter regarding, for example, the position of the catheter and the forces exerted on the tip of the catheter. Applicants have overcome various design constraints to provide catheters having, among other things, flexible circuits that can provide feedback in a safe and effective manner.

Disclosed herein are flexible circuits. The flexible circuit may include a substantially planar substrate including a first portion of a first shape (e.g., circular) and a second portion of a second shape (e.g., rectangular or substantially rectangular) different from the first shape. A first substantially planar force sensing coil may be disposed on the first portion and a first substantially planar position coil may be disposed on the second portion. Additionally, the second portion may include a first section connected to a second section by a first connector section such that the first substantially planar position coil may be disposed on the first section. In such embodiments, the second substantially planar position coil may also be disposed on the second section such that preferably the first section and the first substantially planar position coil form a substantial mirror image of the second section and the second substantially planar position coil. Thus, the first substantially planar position coil may have a clockwise orientation and the second substantially planar position coil may have a counter-clockwise orientation. Alternatively, the first substantially planar position coil may have a counter-clockwise orientation and the second substantially planar position coil may have a clockwise orientation.

In further embodiments, the substantially planar substrate may further comprise a third portion comprising a third section connected to a fourth section by a second connector section. A third substantially planar position coil may be disposed on the third section and a fourth substantially planar position coil may be disposed on the fourth section. Similar to the first and second sections, the third and third substantially planar position coils mirror the fourth and fourth substantially planar position coils.

In further embodiments, the substantially planar substrate may comprise a fourth portion connected to and disposed between the first, second and third portions, for example by a third, fourth and fifth connector section, respectively.

Additional connector sections may also be provided. For example, the substantially planar substrate may also include a sixth connector section connecting the first section to the second section and a seventh connector section connecting the third section to the fourth section.

The various coils described above may be connected to pads provided on the fourth portion. For example, a portion of the second substantially planar position coil may extend from the second section of the second portion to the first weld point on the fourth portion via the first connector section and the first section of the second portion. Additionally, the extension of the force sensing coil may extend to a second weld point on the fourth portion.

As mentioned, the first portion may have a circular shape. The circular shape may include a trilobal shape having a fifth section on which the first substantially planar force sensing coil is disposed, a sixth section on which the second substantially planar force sensing coil is disposed, and a seventh section on which the third substantially planar force sensing coil is disposed.

In any embodiment, the substrate may be fabricated by a photolithographic process. The substantially planar substrate may include between two layers and ten layers, for example, four layers. In addition, an additional material (e.g., polyimide) may be disposed on at least one of the second portion, the third portion, and the fourth portion.

In any embodiment, as its name implies, the flexible circuit is flexible. In addition, the flexible circuit is dimensioned such that deformation of the second and third connectors reduces the distance between the second and third portions to be approximately equal to the maximum width of the first portion. The deformation of the second connector and the deformation of the third connector may be circular deformations. Additionally, deformation of the fourth connector may cause the second section to contact and overlap the first section, and deformation of the fifth connector may cause the fourth section to contact and substantially overlap the third section. Additionally, deformation of the third connector may align the second substantially planar position coil with the first substantially planar position coil, and deformation of the fourth connector may align the fourth substantially planar position coil with the third substantially planar position coil.

The flexible circuit may be assembled into a catheter according to the following methods and variations. First, the first portion may be oriented parallel to a face of the spring that is oriented transverse to a longitudinal axis of the spring. The first portion may then be attached to the face of the spring. Second, the second and third portions may be oriented parallel to the two outer portions of the coupling sleeve, respectively. The second and third portions may then be connected to the two outer surface portions, respectively. Third, the coupling sleeve may be coupled to an outer sleeve. Fourth, a spring may be coupled to the catheter tip. In some variations, the faces of the spring may be oriented at an angle greater than about 60 degrees and less than 90 degrees relative to the longitudinal axis of the spring. Typically, the spring may be manufactured with such properties prior to assembly. For example, the angle may be about 80 degrees.

Fifth, a gap between the outer sleeve and at least one of the second, third, and fourth portions may be filled. The step of filling the gap comprises providing an additional material (e.g. polyimide) on at least one of the second, third and fourth portions. The additional material may be provided onto at least one of the second portion, the third portion and the fourth portion before or after the coupling sleeve is coupled to the outer sleeve.

As used herein, the terms "substantially planar" and "substantially planar" should be understood to indicate a planar configuration of an object or an approximately planar configuration of the object that would be acceptable to one skilled in the art for the intended use of the object.

Drawings

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter described herein, it is believed that the subject matter will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and wherein:

FIG. 1 is an illustration of a system for assessing electrical activity in a heart of a living subject and providing therapy to the heart using a catheter;

FIG. 2 depicts a flexible circuit member of the catheter of FIG. 1;

FIG. 3 depicts the flexible circuit member of FIG. 2 in a modified configuration;

FIG. 4 depicts another flexible circuit member of the catheter of FIG. 1;

FIG. 5 depicts a spring member of the catheter of FIG. 1;

FIG. 6 depicts a distal portion of the catheter of FIG. 1 in a partially assembled configuration;

FIG. 7 depicts a distal portion of the catheter of FIG. 1 in a further partially assembled configuration; and

fig. 8 depicts a cross-section taken through line a-a of fig. 6.

Detailed Description

The following should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. The description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.

As used herein, the term "about" or "approximately" for any numerical value or range indicates a suitable dimensional tolerance that allows the component or collection of elements to achieve its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values ± 10% of the recited value, e.g., "about 90%" may refer to a range of values from 81% to 99%. Additionally, as used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject and are not intended to limit the system or method to human use, but use of the subject invention in a human patient represents a preferred embodiment.

The subject matter disclosed herein relates to structures within a catheter that can be used to provide feedback to a user of an ablation catheter (e.g., an electrophysiologist) regarding the catheter position and forces exerted on the catheter tip and any electrodes disposed on the catheter. These structures must fit within the small inner diameter of the catheter (e.g., often equal to or less than about 0.1 inch), but overcome various design constraints associated with the small inner diameter to reliably provide feedback. For example, a metal coil may be used to detect a position within a magnetic field. Roughly, larger and thicker coils with more turns are easier to detect than smaller and thinner coils with fewer turns; however, due to the small space within the catheter, the coil must be small and thin to fit within. In addition, when such coils are fabricated as traces on a circuit board or flexible circuit via a photolithographic process, the process limits the trace pitch. While this option can be used to lithographically increase the thickness of the circuit by additional layers, this option has two drawbacks. First, it is expensive because the manufacturing cost is proportional to the number of layers. That is, flexible circuits having more layers are more costly to manufacture than flexible circuits having fewer layers, all other things being equal. Second, the non-linearity of the yield is also proportional to the number of layers. That is, yield from the coil is compromised because the non-linearity of yield increases with the number of traces. These design challenges are compounded by the inclusion of additional structures adjacent the location traces, including the flushing structure and the force measurement components that must be able to reliably provide acrylic measurements. In addition, crosstalk interference that may arise from packaging the structure in a compact space should be considered. The same should be true for the need for a safety product that is convenient to assemble and route and that has positive patient outcomes.

Fig. 1 is an illustration of a system 10 for assessing electrical activity and performing an ablation procedure on a heart 12 of a living subject. The system includes a catheter 14, the catheter 14 being percutaneously inserted by an operator 16 through the vascular system of the patient into a chamber or vascular structure of the heart 12. An operator 16, typically a physician, brings a distal tip 18 of the catheter into contact with the heart wall, for example at an ablation target site. The electrically active maps may be prepared according to the methods disclosed in U.S. Pat. Nos. 6,226,542 and 6,301,496, and in commonly assigned U.S. Pat. No. 6,892,091, the disclosures of which are hereby incorporated by reference in their entirety. An article of commerce embodying elements of system 10 may be under the trade name

The system is available from Jiansheng corporation, Inc.,33Technology Drive, Irvine, CA,92618, technical Avenue, Inc.,33, Inc., of Arwan, Calif. under reference number 92618.

The areas determined to be abnormal, for example, by evaluation of an electrically active map, may be ablated by applying thermal energy, for example, by passing radio frequency current through wires in the catheter to one or more electrodes at the distal tip 18, which apply the radio frequency energy to the target tissue. Energy is absorbed in the tissue, heating the tissue to a point (typically above 50 ℃) where the tissue permanently loses its electrical excitability. This procedure creates nonconductive foci in the cardiac tissue that can interrupt the abnormal electrical pathways that lead to arrhythmias. Such principles may be applied to different ventricles to diagnose and treat many different types of arrhythmias.

The catheter 14 generally includes a handle 20 with suitable controls thereon to enable the operator 16 to manipulate, position and orient the distal end of the catheter as required for ablation. To assist the operator 16, the distal portion 18 of the catheter 14 or a portion adjacent to the distal portion 18 of the catheter 14 contains a position sensor (e.g., a trace or coil (discussed below)) that provides a signal to a processor 22 located in a console 24.

Ablation energy and electrical signals may be transmitted back and forth between heart 12 and console 24 via cable 38 through one or more ablation electrodes 32 located at or near distal tip 18. Pacing signals and other control signals may be communicated from console 24 to heart 12 via cable 38 and electrodes 32.

A wire connection 35 connects the console 24 with the body surface electrodes 30 and other components of the positioning subsystem for measuring the position and orientation coordinates of the catheter 14. Processor 22 or another processor may be an element of the positioning subsystem. The electrodes 32 and body surface electrodes 30 may be used to measure tissue impedance at the ablation site as taught in U.S. patent 7,536,218 to Govari et al, which is incorporated herein by reference in its entirety. A temperature sensor (not shown), typically a thermocouple or thermistor, may be mounted on or near each of the electrodes 32.

The console 24 typically contains one or more ablation power generators 25. The catheter 14 may be adapted to conduct ablative energy, such as radiofrequency energy, ultrasound energy, cryoenergy, and laser-generated optical energy, to the heart using any known ablation technique. Such methods are disclosed in commonly assigned U.S. Pat. Nos. 6,814,733, 6,997,924, and 7,156,816, which are incorporated herein by reference in their entirety.

The positioning subsystem may also include a magnetic position tracking arrangement that determines the position and orientation of the catheter 14 by generating magnetic fields in a predefined working volume and sensing these fields at the catheter using coils or traces disposed within the catheter (typically adjacent the tip). The positioning subsystem is described in U.S. patent 7,756,576, and in the above-mentioned U.S. patent 7,536,218, which are hereby incorporated by reference in their entirety.

Operator 16 may observe and adjust the function of catheter 14 via console 24. The console 24 includes a processor, preferably a computer with appropriate signal processing circuitry. The processor is coupled to drive a monitor 29. The signal processing circuitry typically receives, amplifies, filters, and digitizes signals from catheter 14, including signals generated by sensors such as electrical sensors, temperature sensors, and contact force sensors, and a plurality of position sensing coils or traces located distal to catheter 14. The digitized signals are received and used by the console 24 and positioning system to calculate the position and orientation of the catheter 14 and to analyze the electrical signals from the electrodes and contact force sensors.

The subject matter disclosed herein relates to structures within a catheter that can be used to provide feedback to an operator 16. In particular, the feedback is related to the position of the catheter and its tip, as well as the forces exerted on the tip of the catheter and any electrodes disposed on the tip of the catheter. These structures must fit within the small inner diameter of the catheter (e.g., often equal to or less than about 0.1 inch), but overcome various design constraints associated with the small inner diameter to reliably provide feedback. For example, a metal coil may be used to detect a position within a magnetic field. Generally, larger and thicker coils are easier to detect than smaller and thinner coils, however, due to the small space within the catheter, the coils must be small and thin to fit within. In addition, when such coils are fabricated as traces on a circuit board or flexible circuit via a photolithographic process, the process limits the trace pitch. While the option may be used to lithographically increase the thickness of the traces by additional layers, this option has two drawbacks. First, it is expensive because more layers cost more than fewer layers. Second, as long as the yield non-linearity increases with the number of traces, the yield from the coil suffers. These design challenges are compounded by the inclusion of additional structures of adjacent location traces that must be able to reliably provide acrylic measurements, and the lack of crosstalk interference that can arise from packaging the structure in a compact space, as well as the need for a security product that is convenient to assemble and route and positive patient outcome.

Fig. 2 reflects a flexible circuit 110, which flexible circuit 110 may be employed within a catheter, such as catheter 14, to provide position and force related signals to a processor in console 24. The flexible circuit 110 includes a substantially planar substrate 112, the substantially planar substrate 112 having a first portion 114 of a first shape (e.g., circular or tri-lobal as shown) and a second portion 116 of a second shape (e.g., substantially rectangular or polygonal as shown). The first portion 114 and the second portion 116 generally have different shapes because, as will be explained below, the first portion 114 is assembled parallel to the longitudinal axis of the catheter such that the first portion 114 should be elongated, and the first portion 114 is assembled transverse to the longitudinal axis of the catheter such that the first portion 114 should conform to the inner diameter of the catheter (i.e., have a maximum width or diameter that is less than or about equal to the inner diameter of the catheter). Nonetheless, the first portion 114 and the second portion 116 may be similar in shape. The substrate may be formed of any suitable material that is electrically non-conductive and capable of withstanding high temperatures, such as polyimide, polyamide, or Liquid Crystal Polymer (LCP).

The substrate 112 may also include additional portions, such as a third portion 130 and a fourth portion 142. Each of these portions may also include various sections. As mentioned, the first portion 114 may have a trilobal shape. Thus, the first portion 114 may have three sections, namely, section 160, section 162, and section 164. The second portion 116 may include a section 122 and a section 124, and at least one connector section, such as 126 or 150, connecting the section 122 to the section 124. The third portion 130 may have a similar structure to the second portion 116 and may include a section 132 and a section 134, and at least one connector section, such as 136 or 152, connecting the section 132 to the section 134. The fourth portion 142 may include at least three

connector sections

144, 146, and 148, the at least three

connector sections

144, 146, and 148 connecting the fourth portion 142 to the first, second, and

third portions

114, 116, and 130.

Electronic components may be incorporated into the substrate 112 and various portions and sections thereof. For example, a substantially planar coil or trace for measuring a force-related signal (i.e., a force sensing coil or trace) may be coupled to the first portion 114. Specifically, coil 118 may be combined with segment 160, coil 170 may be combined with segment 162, and coil 172 may be combined with segment 164. The

coils

118, 170, and 172 may be separate from each other as shown, or the

coils

118, 170, and 172 may each be connected to one or both of the other coils. A portion of each coil or a partial extension of each coil may extend from the coil to a weld 168 located on the fourth portion 142 and be welded to the weld 168. In the case where the three coils are separated from each other, each coil should include a respective extension (i.e., 166, 174, and 176). However, in the case of connecting three coils, only one or two extensions may be necessary. Where the coils are separated from one another, the signal generated in each of the coils may be used to provide additional detail of the force, such as an off-center force or an indication of the off-axis direction of the force. As shown, each coil on the first portion 114 includes approximately five turns. However, because signal strength is a function of the number of turns, the number of turns can be maximized based on the size of each segment and the pitch achievable by the photolithographic process.

Planar coils or traces for measuring position-related signals (i.e., position coils or traces) may also be incorporated into the second portion 116 and the third portion 130. Coil 120 may be combined with segment 122, coil 128 may be combined with segment 124, coil 138 may be combined with segment 132, and coil 140 may be combined with segment 134. Each of these coils may extend to a weld 168 on the fourth portion 142. For example, coil 120 may include extensions 154 connected to weld 168 via connector section 146, and coil 128 may include extensions 156 connected to weld 168 via connector section 126, section 122, and connector section 146. As shown, each coil on the first and second portions 116, 130 includes approximately five turns. However, because signal strength is a function of the number of turns, the number of turns may be maximized based on the size of the

sections

122, 124, 132, and 134 and the spacing achievable by the photolithographic process.

Various symmetries are reflected in fig. 2. For example, the entire substrate is symmetrical about a midline through the center of the first portion 114, such that the second portion 116 is disposed laterally to one side of the first portion 114 and the fourth portion 142, and such that the third portion 130 is disposed laterally to the other side of the first portion 114 and the fourth portion 142. Thus, the fourth portion 142 is disposed between the first portion 114, the second portion 116, and the third portion 130. In addition, section 122 and section 124 are mirror images of each other, and coil 120 is mirror image of coil 128 except for extension 156. The same is true for

sections

132 and 134 and coils 138 and 140. Thus, and as shown, the wind of coil 120 and coil 132 may be clockwise (i.e., have a clockwise orientation), while the wind of coil 128 and coil 134 may be counter-clockwise (i.e., have a counter-clockwise orientation). Alternatively, the wind of coils 120 and 132 may be counter-clockwise and the wind of

coils

128 and 134 may be clockwise.

The substrate 112 may be a single layer. Alternatively, the substrate 112 may include between two and ten layers, for example, four layers. Thus, the coil can be made thicker by adding layers. However, as described above, increased nonlinearity in signal yield is caused by layer thickening. The flexibility of the flexible circuit 110 enables a solution to this tradeoff. Specifically, referring to fig. 3, segment 124 may be folded over the top of segment 122 by deforming or bending connector 126 and connector 150 to contact and overlap the top of segment 122 such that coil 128 is aligned with coil 120. Similarly, by deforming or bending the connector 136 and the connector 152, the section 134 may be folded over the top of the section 132 to contact and overlap the top of the section 132 such that the coil 140 is aligned with the coil 138. Although connector 150 and connector 152 are optional, connector 150 and connector 152 may assist in aligning the coils with each other by reducing relative rotation between the segments. For example, if the substrate 112 is four layers, after folding the section 124 onto the section 122, the coil 120 and the coil 128 form a combined coil having eight layers. Although the tile density may increase due to increased area, the yield of the combined coil does not suffer from increased non-linearity as does an eight-layer coil fabricated in an eight-layer substrate.

A thinner substrate (e.g., four layers) has an advantage over a thicker substrate (e.g., eight layers) in that the thinner substrate (e.g., four layers) is more easily deformed or bent, which facilitates assembly of the flexible circuit 110 to other catheter components, and ultimately facilitates assembly of the flexible circuit 110 within the inner diameter envelope of the catheter, as will be described in detail below. Thus, the flexible circuit 110 allows for a thick coil without increased non-linearity of the signal and increased stiffness of the substrate.

Fig. 4 reflects another component of catheter 14 (flex circuit 180), flex circuit 180 including a substrate 182 and one or more coils 184. The structure of the flexible circuit 180 is similar to the structure of the first portion 114 of the flexible circuit 110. However, in various embodiments, the number or spacing of the coils may vary, and the various coils on the three sections may be separate from each other or integral with each other.

Fig. 5 reflects another component of the catheter 14 (coil spring 190), the coil spring 190 including a top surface 192, a bottom surface 194, and various arms 196 that may be used to assemble the spring 190 to other components of the catheter 14. The spring 190 has a known or predetermined spring constant that relates distance to force according to Hooke's Law. Together, the flex circuit 180, the first portion 114 of the flex circuit 110, and the coil spring 190 constitute a subassembly that can receive electrical signals from the console 24 and provide electrical signals to the console 24 that can be processed to determine the force (e.g., acrylic force) exerted on the tip 18 of the catheter 14. Specifically, one or more first cables (within cable harness 198 of fig. 6 and 7) connected to console 24 at one end may also be connected to solder joints 168 of fourth portion 142 of flex circuit 110 at an opposite end, solder joints 168 being connected to

coils

118, 170, and 172 on

segments

160, 162, and 164 of first portion 114 via

coil extensions

166, 174, and 176, respectively. One or more second cables (also within cable bundle 198) connected at one end to console 24 may also be connected at an opposite end to one or more coils 184 on flex circuit 180. The electrical signal (e.g., having an RF frequency) from the console 24 can be used to power a coil on the first portion of the flexible circuit 110 or a coil on the flexible circuit 180. Whichever set of coils receives power from the console 24 may be considered a transmitter because the set of coils emits an electromagnetic field that varies according to the frequency of the signal received from the console 24. A set of coils that are not powered by the console 24 may be considered a receiver because the set of coils act like an antenna in response to an electromagnetic field from a transmitter. Thus, the receiver generates an electrical signal that can be transmitted to the console 24 for analysis. The electrical signal generated by the receiver is dependent on the distance between the receiver and the transmitter, such that the electrical signal generated by the receiver can be correlated to the distance between the receiver and the transmitter.

By adhering the receiver (here, the coil on the first portion 114 of the flexible circuit 110) to the top surface 192 of the spring 190 and the transmitter (here, the coil on the flexible circuit 180) to the bottom surface of the spring 180, and routing them as described above, the electrical signal generated in the receiver may be associated with a compressive displacement in the spring (e.g., approximately 100 nanometers), and thus a force against the tip 18 of the catheter 14 that causes the spring 180 to compress. In use, console 24 may process these signals and use the signals to adjust the amount of ablation energy supplied to the electrodes. For example, when the signal indicates that the spring is in a relaxed state (i.e., not compressed), this may be perceived as an indicator that the tip 18 of the catheter 14 is not in contact with tissue and thus no ablation energy should be supplied to the electrode. An indication of the information (e.g., in force (such as newtons)) may also be provided to the operator 16 on the monitor 29. This information may be used to be provided directly to the operator 16 as long as the information can help the operator 16 avoid damaging the tissue by pressing the tip 18 against the tissue with too much force.

The top surface 192 and the bottom surface 194 of the spring 190 may be parallel to each other and oriented transverse to the longitudinal axis of the spring (e.g., at an angle greater than about 60 degrees and less than 90 degrees (e.g., about 80 degrees)). The receivers and transmitters attached to the top and bottom surfaces of the spring are then similarly angled. The inventors have determined that a transverse, but non-perpendicular, angle increases the sensitivity of the receiver because the distance between the transmitter and receiver is minimized compared to if the transmitter and receiver were provided perpendicular to the longitudinal axis of the spring and ultimately perpendicular to the longitudinal axis of the catheter.

Fig. 6 and 7 show the catheter 14 at two different steps of assembly of the catheter 14. Fig. 8 is a cross-section of catheter 14 taken along line a-a in fig. 6, but additional discussion regarding flexible circuit 110 removes or simplifies various components for clarity. Fig. 6 shows the flexible circuit 110 when assembled to the spring 190 and the coupling sleeve 200. Although not seen, the first portion 114 of the flexible circuit 110 is adhered to the top surface 192 of the spring 190 and the flexible circuit 180 is adhered to the bottom surface 194 of the spring 190. In fig. 7, the tip 18, which may itself include one or more ablation electrodes 32 and include various irrigation holes 214, is attached to a spring 190. Also shown in fig. 6 and 7 is a cable harness 198. The cable harness 198 includes a set of cables, although not visible, that are connected to the pads 168 on the fourth portion 142 of the flexible circuit 110, and thus to the various coils or traces on the flexible circuit 110, and to the coils or traces 184 on the flexible circuit 180. As seen in fig. 6-8, the flexible circuit 110 is no longer planar. Instead, the flexible circuit 110 has been deformed to have a shape with a partially circular and partially triangular cross-section. The section 124 of the second portion 116 is the most readily visible section of the flexible circuit 110 in fig. 6 and 7. Various sides of section 122, section 132, and section 134, as well as connector 126, connector 136, connector 146, connector 150, and connector 152 are also visible in these figures. As seen, these connectors have been deformed into a bent or curved configuration for attachment to the coupling sleeve 200. Specifically, section 122 is adhered to a substantially planar surface 202 of sleeve 200, and section 132 is adhered to a substantially planar surface 204 of sleeve 204. So assembled, these portions of the flexible circuit 110 can be considered to have a triangular cross-section. In addition, connector 146 is adhered to a rounded (or arcuate) surface 206 of sleeve 200, and connector 148 is adhered to a rounded (or arcuate) surface 208 of sleeve 200. So assembled, these portions of the flexible circuit 110 can be considered to have a circular (or arcuate) cross-section. The fourth portion 142 may also be adhered to the substantially planar surface 210 of the sleeve 200.

When assembled to the sleeve 200, the diameter or width of the circular portion of the cross-section of the flexible circuit 110 is equal to or approximately equal to the diameter or maximum width of the first portion 114, which is also equal to or approximately equal to the maximum width (or base) of the triangular portion of the cross-section of the flexible circuit 110 when assembled to the sleeve 100. Thus, when assembled, the flexible circuit 110 may be easily inserted into an outer tube or sleeve 216 (fig. 1), the outer tube or sleeve 216 providing the outer surface of the catheter 14 and defining an inner diameter to which the component parts of the catheter 14 (e.g., the flexible circuit 110, the spring 180, the sleeve 200) must fit. To help prevent soft spots under the sleeve 216 caused by gaps between the substantially planar outer surfaces of the

segments

124 and 134 and the portion 142 on the one hand, and the curvature of the sleeve 216 on the other hand, these gaps may be filled by including additional material (e.g., adhesive 218 and polyimide layer 220) on the segments 124 and 134 (of the second and third portions 116 and 130, respectively) and the portion 142. The polyimide layer 220 may be manufactured separately from the flexible circuit 110 and adhered to the flexible circuit 110, or the polyimide layer 220 may be an integral part of the flexible circuit 110, formed during the same lithographic process as the rest of the flexible circuit 110. Polyimide layer 220 may be formed with a series of substantially planar steps or curves that interpose sleeve 216 within the layer.

The flexible circuit 110 may be assembled into the catheter 14 as follows. First, a flexible circuit 110 may be provided. Section 124 of second portion 116 may be folded over section 122 of second portion 116 by deforming connector 126 and connector 150 (if included) to overlap section 122 and contact section 122. Section 134 of third portion 130 may be folded over section 132 of third portion 130 by deforming connector 136 and connector 152 (if included) to overlap section 132 and contact section 132. The first portion 114 of the flexible circuit 110 can be oriented parallel to a top surface 192 of the spring 190, the top surface 192 of the spring 190 being oriented transverse to the longitudinal axis of the spring 190 (e.g., less than 30 degrees from perpendicular to the longitudinal axis of the spring 190). The first portion 114 may then be adhered to the top surface 192 of the spring 190. A coupling sleeve 200 having a substantially planar surface portion may be provided and the coupling sleeve 200 oriented such that a longitudinal axis of the coupling sleeve 200 is aligned with a longitudinal axis of the spring. The second portion 116 and the third portion 130 may be oriented parallel to respective substantially planar surface portions of the sleeve 200. The second portion 116 and the third portion 130 may then be adhered to respective substantially planar surface portions of the sleeve 200. The sleeve 200 adhered to the flexible circuit 110 may then be coupled or inserted into the outer sleeve 216. Finally, the tip 18 may be attached to a spring 190. As long as the tip 18 is not attached to the spring 190, the flexible circuit 180 may adhere to the bottom surface 194 of the spring 190 at virtually any step of the process.

Any of the examples or embodiments described herein may include various other features in addition to or in place of those described above. The teachings, expressions, embodiments, examples, etc. described herein should not be considered as independent of each other. Various suitable ways in which the teachings herein may be combined should be apparent to one of ordinary skill in the art in view of the teachings herein.

Having shown and described exemplary embodiments of the subject matter contained herein, further modifications of the methods and systems described herein can be effected, with appropriate modification, without departing from the scope of the claims. Further, where methods and steps described above indicate certain events occurring in a certain order, it is intended herein that certain steps need not be performed in the order described, but rather may be performed in any order, so long as the steps allow the embodiments to function for their intended purposes. Thus, if variations of the invention exist and fall within the true scope of the disclosure or equivalents thereof as may be found in the claims, then this patent is intended to cover such variations as well. Many such modifications will be apparent to those skilled in the art. For example, the examples, embodiments, geometries, materials, dimensions, ratios, steps, etc., described above are illustrative. Thus, the claims should not be limited to the specific details of construction and operation shown in this written description and the drawings.

Claims

1. A flexible circuit, comprising:

a substantially planar substrate comprising a first portion of a first shape and a second portion of a second shape, the second shape being different from the first shape;

a first substantially planar force sensing coil disposed on the first portion; and

a first substantially planar position coil disposed on the second portion.

2. The flexible circuit of claim 1, wherein the second portion comprises a first section connected to a second section by a first connector section, the first substantially planar position coil being disposed on the first section and a second substantially planar position coil being disposed on the second section.

3. The flexible circuit of claim 2, wherein the first segment and the first substantially planar position coil form a substantial mirror image of the second segment and the second substantially planar position coil.

4. The flexible circuit of claim 3, wherein the first substantially planar position coil has a clockwise orientation and the second substantially planar position coil has a counterclockwise orientation.

5. The flexible circuit of claim 3, wherein the substantially planar substrate further comprises a third portion comprising a third segment connected to a fourth segment by a second connector segment, a third substantially planar position coil disposed on the third segment and a fourth substantially planar position coil disposed on the fourth segment, and

wherein the third section and the third substantially planar position coil mirror the fourth section and the fourth substantially planar position coil.

6. The flexible circuit of claim 5, wherein the substantially planar substrate further comprises a fourth portion connected to and disposed between the first, second, and third portions.

7. The flexible circuit of claim 6, wherein the fourth portion is connected to the first, second, and third portions by a third, fourth, and fifth connector sections, respectively.

8. The flexible circuit of claim 7, wherein the substantially planar substrate further comprises a sixth connector section connecting the first section to the second section and a seventh connector section connecting the third section to the fourth section.

9. The flexible circuit of claim 6, wherein a portion of the second substantially planar position coil extends from the second section of the second portion to a first bond point on the fourth portion via the first connector section and the first section of the second portion.

10. The flexible circuit of claim 9, wherein the extension of the force sensing coil extends to a second bond pad on the fourth portion.

11. The flexible circuit of claim 10, wherein the force sensing coil is configured to receive an electromagnetic signal from a transmitter coil.

12. The flexible circuit of claim 6, wherein the first shape comprises a circular profile and the second shape comprises a substantially rectangular profile.

13. The flexible circuit of claim 12, wherein the circular shape comprises a trilobal shape having a fifth section, a sixth section, and a seventh section, the first substantially planar force sensing coil being disposed on the fifth section, a second substantially planar force sensing coil being disposed on the sixth section, and a third substantially planar force sensing coil being disposed on the seventh section.

14. The flexible circuit of claim 6, wherein the substantially planar substrate is comprised between two layers and ten layers.

15. The flexible circuit of claim 6, wherein additional material is disposed on at least one of the second portion, the third portion, and the fourth portion.

16. The flexible circuit of claim 15, wherein the additional material comprises polyimide.

17. The flexible circuit of claim 16, wherein the additional material further comprises an adhesive.

18. A flexible circuit, comprising:

a substantially planar substrate comprising

A first portion having a first substantially planar force sensing coil disposed thereon,

a second portion having a first substantially planar position coil disposed thereon,

a third portion having a second substantially planar position coil disposed thereon, an

A fourth portion disposed between and connected to the first, second, and third portions by first, second, and third connectors, respectively, such that deformation of the second and third connectors reduces a distance between the second and third portions to approximately equal a maximum width of the first portion.

19. The flexible circuit of claim 18, wherein the deformation of the second connector and the deformation of the third connector comprise circular deformations.

20. The flexible circuit of claim 18, wherein the second portion comprises a first segment connected to a second segment by a fourth connector and the third portion comprises a third segment connected to a fourth segment by a fifth connector, such that deformation of the fourth connector causes the second segment to contact and overlap the first segment and such that deformation of the fifth connector causes the fourth segment to contact and substantially overlap the third segment.

21. The flexible circuit of claim 20, wherein the first section comprises the first substantially planar position coil, the second section comprises a second substantially planar position coil, the third section comprises a third substantially planar position coil, and the fourth section comprises a fourth substantially planar position coil, such that the deformation of the third connector aligns the second substantially planar position coil with the first substantially planar position coil, and such that the deformation of the fourth connector aligns the fourth substantially planar position coil with the third substantially planar position coil.

22. The flexible circuit of claim 18, wherein additional material is disposed on at least one of the second portion, the third portion, and the fourth portion.

23. The flexible circuit of claim 22, wherein the additional material comprises polyimide.

24. A method of assembling a catheter including a substantially planar flexible circuit, comprising:

providing a flexible circuit comprising a substantially planar substrate having

a second portion having a first substantially planar position coil disposed thereon, an

A third portion having a second substantially planar position coil disposed thereon;

orienting the first portion parallel to a face of a spring, the face of the spring oriented transverse to a longitudinal axis of the spring;

attaching the first portion to the face of the spring;

orienting the second portion and the third portion to be parallel to two outer surface portions of a coupling sleeve, respectively; and

attaching the second portion and the third portion to the two outer surface portions.

25. The method of claim 24, further comprising coupling the coupling sleeve to an outer sleeve.

26. The method of claim 25, further comprising coupling the spring to a catheter tip.

27. The method of claim 26, wherein the face of the spring is oriented at an angle greater than about 60 degrees and less than 90 degrees relative to the longitudinal axis of the spring.

28. The method of claim 27, wherein the angle is about 80 degrees.

29. The method of claim 26, further comprising filling gaps between the outer sleeve and at least one of the second portion, the third portion, and the fourth portion.

30. The method of claim 29, wherein the step of filling the gap comprises providing additional material on at least one of the second portion, the third portion, and the fourth portion.

31. The method of claim 30, wherein the additional material comprises polyimide.